1. Technical Field
The present disclosure relates to a light emitting diode (LED), a backlight module and a liquid crystal display (LCD) apparatus.
2. Description of Related Art
As semiconductor technology advances, light emitting diodes (LEDs) have been extensively applied in various applications, such as traffic signs, large display bulletins, scanners and liquid crystal display apparatuses to provide a light source needed by an electronic product.
Typical LEDs are usually semiconductor devices which use III-V compounds, such as GaP, GaAs, and so on. The light emitting principle is to convert electric energy into light. In other words, by applying a current to the compound semiconductor, redundant energy is released in a form of light through the combination of electrons and electron holes, thus achieving a light emitting effect. The LED has advantages of fast response time (about 10−9 second), small volume, low power consumption, low pollution risk (no mercury contained), high reliability, good adaptation to mass production, and so on, and therefore gradually replaces conventional fluorescent lamps and incandescent bulbs.
However, when the LEDs are applied in an optical system which requires a polarized light source (for example, an LCD apparatus), a polarization converter is needed in the optical system so that the light source generated by the LEDs can be converted in to light with a particular polarization direction by the polarization converter. FIG. 1A is a schematic view of an LCD apparatus 100 known to the inventor(s). The LCD apparatus 100 includes a backlight module 110, a plurality of polarizers 120 and an LCD panel 130. The light generated by the backlight module 110 has no particular polarization type, but includes a combination of P polarized light and S polarized light. Thus, a polarized light source is obtained by the polarizers 120.
However, the polarizers 120 not only increase the manufacturing cost of the LCD apparatus 100, but also reduce the light utilization rate. Specifically, the light with the polarization direction parallel to the transmittance axis of the polarizers 120 can pass through the polarizers 120 whereas the light with the polarization direction perpendicular to the transmittance axis of the polarizers 120 will be absorbed by the polarizers 120. Therefore, only a portion of the light will pass through the polarizers 120 and a portion of light will be shielded. Consequently, the light utilization rate of the backlight module 110 is low and the light utilization effect of the LCD apparatus 100 is not as desired.